1. Field of the Invention
The present invention relates to a voice input/output apparatus which has a voice recognition device and a synthesizing type voice response device, so that the apparatus may respond to an input voice with an output voice.
2. Description of the Prior Art
With recent advances in voice processing technique, a voice input/output apparatus is proposed which is of the type having the function of voice recognition and response by synthesis of a voice. However, in the conventional voice input/output apparatus of this type, when it is necessary to recognize an input voice and to process input data during response by a voice, the output voice for response is mixed in the desired input voice, so that the recognition ratio of the input voice is degraded.
FIG. 1 is a block diagram showing the configuration of a conventional voice input/output apparatus of this type. In the conventional voice input/output apparatus of this type, a data processor for generating output data for response with a voice is interposed between a voice recognition device and a voice response device. FIG. 1, however, shows only the voice response device and the voice recognition device of totally different systems for voice conversion in separate conditions. In the example shown in FIG. 1, the voice response device is a voice synthesizing unit of the PARCOR type, that is a, partial auto-correlation type. However, the voice may be synthesized in any manner. In the conventional voice input/output apparatus of the configuration shown in FIG. 1, a voice response device shown above the dotted line in FIG. 1 stores voice source data for response with voice frequency data (a voiced sound if the frequency is 0 and an unvoiced sound if the frequency is more than 0) in a voice source data register, and stores a PARCOR coefficient representing vocal resonance characteristics for PARCOR type voice synthesis in a PARCOR coefficient register 2. The voice response device reads out voice source data from the voice source register 1 and makes a voice source circuit 3 output a pulse train signal obtained by modulation. The pulse train signal is supplied to a PARCOR synthesizing operation unit 4. In response to the PARCOR coefficient read out from the PARCOR coefficient register 2, the PARCOR synthesizing operation unit 4 performs a synthesizing operation of PARCOR type voice synthesis to generate a digital signal representing a voice corresponding to the voice source data. The digital signal representing the voice corresponding to the voice source data is supplied to a digital/analog converter 5 (to be referred to as a D/A converter hereinafter) which converts the input digital signal into an analog voice signal. The analog voice signal obtained from a synthesized voice output terminal 6 is supplied to a speaker 7 which generates a desired output response voice. The PARCOR synthesizing operation unit 4 synthesizes a voice by passing the pulse train signal output from the voice source circuit 3 through a filter which simulates the resonance characteristics of a vocal cord. This filter comprises a delay element, a correlator, two multipliers, and two adders. The characteristic parameter generally used in the PARCOR synthesizing operation unit is the data obtained by adding the PARCOR coefficient to the voice source data.
In the voice recognition device shown below the dotted line in FIG. 1, the analog voice signal from a microphone 8 is fed through a voice input terminal 9 to an analog-digital converter 10 (to be referred to as an A/D converter) which converts the input analog voice signal into a digital voice signal. The digital voice signal is supplied to a voice recognition device 12 through an input voice output terminal 11. The voice recognition device 12 recognizes the voice data corresponding to the input voice.
In the conventional voice input/output apparatus of the configuration as described above, if, during the generation of the output response voice from the speaker in the voice response device, an input voice signal is supplied to the voice recognition device through a microphone sufficiently separated from the speaker, the synthesized output voice signal from the voice response device is mixed in the input voice signal to the voice recognition device, correct recognition of the input voice cannot be performed, and the ratio of correct voice recognition is significantly degraded.